Izuna Nobel

Tinker, or Yosetsu, is a member of C3 and works at the organization.

Appearance
Yosetsu is a young woman with long blonde hair and blue eyes. She wears a white shirt with half-length sleeves and pink overall shorts with a blue pocket, which often holds her tools. She wears pink and blue matching shoes. Yosetsu is often seen wearing a welding helmet.

History
Not much is known about Yosetsu's past, but she has most likely worked at C3 for a very long time. She knows that a vampire killed Shuhei's father and when she meets Kuro again she states he seems different from before.

Personality
Yosetsu is very laid back and even ditsy at times. She enjoys creating new inventions and getting feedback on them. She is very open with her feelings and will say what is on her mind. Yosetsu is very intelligent, as she is always creating different gadgets and improving existing technology. She can be forceful at times when she becomes passionate about upgrading things, to the point where it scares others off, such as Mikuni, due to her repeated attempts to turn Abel, Mikuni's doll, into a robot. Despite this, she is very light-hearted and open to others. She seems to have no aversion to vampires and enjoys Kuro's cat form. Yosetsu has a good relationship with her coworkers, simply hanging out with them or often suggesting that they play games where the loser buy everyone lunch.

Story
Yosetsu makes her first appearance in chapter 13 when she uses a stun gun on Mahiru. She knocks him completely unconscious and regards this as a mistake, supposing she set the gun too high. She is with C3's Robot Girl, who is assumed to be made by Yosetsu.

While Mahiru is with Shuhei, Yosetsu, along with an unnamed man wearing three pairs of glasses, look after Kuro. Yosetsu sits on a couch next to Glasses Man holding noodles. She calls herself silly because she waited five minutes for her noodles and not the correct time, three minutes. While trying to interrogate Kuro, Glasses Man tells him that Yosetsu over-stunned them and then tells her to apologize. Yosetsu smiles and says no one understands her.

When Mahiru and Kuro stumble into a room at C3, Yosetsu sits in a control room watching them. Shuhei barges in looking for them and asks Yosetsu if they escaped.

Yosetsu then asks Shuhei why Mahiru can't just leave, telling him not to be upset with her for asking. Shuhei is confused and Yosetsu remarks that Sloth is different now. Mikuni then enters and Yosetsu tries to turn Abel into a robot. Mikuni refers to her as Evil Welding Girl and tells her to stop lusting after Abel. Shuhei then locates Mahiru and Kuro and goes after them. Yosetsu decides to join him. Here she pets Kuro, who is in cat form, and calls him cute.

Before Mahiru leaves, Yosetsu introduces herself as Shuhei's coworker and tells him that Shuhei's father was in C3 until a vampire killed him. She says that Shuhei still holds a grudge, but thanks to him he likes vampires a little more than the day before. She then realizes she stun-gunned Mahiru and asks him for feedback.

Tsuyuki Shuhei
Yosetsu gets along well with Shuhei. She knows about his father and that he still holds a grudge against vampires. Yosetsu knows him well enough to realize that Mahiru made him like vampires more than he did before. Yosetsu has a nickname for Shuhei, calling him "Teriyaki", which Shuhei usually ignores or corrects. In a 4-koma she upgrades glasses to make them squirt syrup for shaved ice.

Quotes

 * "Strange...Sloth seems different now." (Chapter 15)
 * "I'll turn Abel into a robot!" (Chapter 15)
 * "I'm Teriyaki's coworker...er, Tsuyuki-kun, I mean...!" (Chapter 15)
 * "A world of hate...is a sad, sad place." (Chapter 15)

Trivia

 * As her actual name has yet to be stated in the manga, the fandom dubbed her as Tinker due to her occupation and hobbies. It was later revealed that her real name is Yosetsu.
 * She does not appear in the anime.